Sensor issue with 1998 Toyota Camry

sounds like you lose power intermittently. Problem might be by the fuse box if you smack it and it works. Loose connection to battery or from battery to fuse box or from fuse box to rest of the car. Check for a loose wire. You can test this by trying to turn something else with power on next time you see check engine light isnt on

Obviously the problem is in the fuse box since you can bang it and the engine starts. Sounds like the PCM is losing power, hence the no check engine light and no start and the stalling with no check engine light. Look in the fuse box for an ECM or PCM fuse and check the connection there. You should also remove the fuse box and with the ignition on wiggle some wires to see which wire makes the check engine light come on and off. With the ignition on and the engine not running the check engine light should be on steady! Hope that helps! Jim